Direction finding, antenna switching AoA Rx (question)

RE: Direction finding, antenna switching AoA Rx (question)

Elfving — Wed, 08 Feb 2023 10:16:59 GMT

Sounds good Chris!

Regards,

Elfving

RE: Direction finding, antenna switching AoA Rx (question)

ChrisRu — Wed, 08 Feb 2023 09:31:52 GMT

Hi,

I open a private ticket on this case because it's

Not related to the original topic.

You had helped me with your reply and I'm happy with the outcome.

Cheers

Chris

RE: Direction finding, antenna switching AoA Rx (question)

Elfving — Wed, 08 Feb 2023 08:54:07 GMT

Maybe so. It seems to be in the final antenna pattern for 3 slots.

Could you show me how you've setup your antenna pattern?

Regards,

Elfving

RE: Direction finding, antenna switching AoA Rx (question)

ChrisRu — Mon, 06 Feb 2023 09:45:00 GMT

Hi Elfving,

I implement what I wrote and can see on my digital oscilloscope the
chip-select (D3) and the switching D0..2 needed for the SP4T chip.

But with every loop back to pattern#2 8us pause measure before repeat the switching.

where the switching is with 16us ok

This might be a configuration issue?

Chris

RE: Direction finding, antenna switching AoA Rx (question)

ChrisRu — Mon, 06 Feb 2023 05:43:54 GMT

Hi Elfving,

I thank you very much for your reply.

The zephyr code example is a bit miss leading in reading, but with your explanation it makes sense to me now.

so I will make my mapping like this:

pattern idx=0 -> antenna 1 (data section)
pattern idx=1 -> antenna 1 (guard & reference)
pattern idx=2 -> antenna 2 (first slot .. repeat )
pattern idx=3 -> antenna 3 (second slot ..)
pattern idx=4 -> antenna 4 (third slot ..)
pattern idx=5 -> antenna 1 (fourth slot ..) for Bluetooth compliant

you mentioned 10 patterns for rotation which make sense to use all 30 iq-samples after the 8 iq-samples of the
reference period (8us). But I think its less tricky for a syhmetric matrix to use 28 iq-samples only and leave 2 iq-samples untouched and use a 4 x 7 matrix which is then average per row and do the SVD calculation.

I have already ported the zsclib module to deal with the complex data. Hope to see the first AoA soon.

Cheers
Chris

RE: Direction finding, antenna switching AoA Rx (question)

Elfving — Fri, 03 Feb 2023 08:51:23 GMT

Hello Chris,

It is set to the first pattern in the data section of the packet, then the second pattern is set to the reference period. You'll then probably use the third pattern in the first switch slot, and the rotation of your patterns then continues back to the third one after finishing.

Note that using a certain pattern doesn't imply using a certain antenna. Given the 4 antennas in your array you can still have eg. 10 patterns in rotation, with multiple patterns being the same and pointing back to the same antenna.

If you are to make a Bluetooth compliant solution then the pattern should always rotate through the reference antenna, this can be done by having the reference antenna (pattern entry 2) as the last entry in the pattern table. It will then be part of the "looped" pattern.

Regards,

Elfving